The Impact of Green R&D Activities on SO₂ Emissions: Evidence from China

Table 4

The results of different green R&D activities on SO₂ emissions (robustness test).

	d1	d2	d3	d4	d5	d6
ln PGDP	0.293^∗∗∗	0.336^∗∗∗	0.197^∗∗	0.219^∗∗	0.259^∗∗∗	0.181^∗
	(0.094)	(0.096)	(0.092)	(0.097)	(0.099)	(0.094)
(ln PGDP)^2	−0.165^∗∗∗	−0.156^∗∗∗	−0.009	−0.166^∗∗∗	−0.158^∗∗∗	−0.012
	(0.029)	(0.029)	(0.033)	(0.029)	(0.029)	(0.033)
ln IND	0.562^∗∗∗	0.532^∗∗∗	0.500^∗∗∗	0.688^∗∗∗	0.655^∗∗∗	0.568^∗∗∗
	(0.11)	(0.11)	(0.104)	(0.104)	(0.105)	(0.1)
ln ENSTR	0.816^∗∗∗	0.787^∗∗∗	0.648^∗∗∗	0.840^∗∗∗	0.809^∗∗∗	0.640^∗∗∗
	(0.084)	(0.085)	(0.082)	(0.085)	(0.086)	(0.084)
ln UR	−0.298	−0.237	0.108	−0.209	−0.159	0.065
	(0.199)	(0.2)	(0.194)	(0.21)	(0.21)	(0.2)
ln GRD	−0.049			−0.056^∗
	(0.032)			(0.032)
ln UGRD		−0.072^∗∗∗	0.072^∗∗		−0.075^∗∗	0.075^∗∗
		(0.03)	(0.034)		(0.03)	(0.035)
ln CGRD		−0.01	0.098^∗∗∗		−0.011	0.102^∗∗∗
		(0.028)	(0.03)		(0.029)	(0.031)
ln lCGRD  ln lUGRD		−0.036^∗∗∗			−0.038^∗∗∗
			(0.005)			(0.005)
_cons	−1.3	−1.232	−2.262^∗∗∗	−2.237^∗∗	−2.116^∗∗	−2.203^∗∗∗
	(0.911)	(0.907)	(0.865)	(0.997)	(0.994)	(0.937)
Heteroscedasticity test	1969.17^∗∗∗	1951.03^∗∗∗	2071.71^∗∗∗	2077.44^∗∗∗	2062.93^∗∗∗	2164.13^∗∗∗
Autocorrelation test	55.793^∗∗∗	67.573^∗∗∗	62.006^∗∗∗	62.119^∗∗∗	60.71^∗∗∗	57.975^∗∗∗
CD	30.151^∗∗∗	29.758^∗∗∗	29.617^∗∗∗	29.493^∗∗∗	29.062^∗∗∗	27.196^∗∗∗
N	510	510	510	510	510	510

Notes: (a) , , and represent a respective significance level at 1%, 5%, and 10%. (b) Values in ( ) stand for the standard error for the coefficient. (c) The null hypothesis for the heteroscedasticity test is that no heteroscedasticity exists. (d) The null hypothesis for the autocorrelation test is that no first-order autocorrelation exists. (e) The CD test examines cross-sectional dependence of residuals. In the CD test, the null hypothesis is cross-section independent. (f) Since DK and FE are similar in results, we only provide FE results.